Which stress test should be ordered for a patient with an EKG showing sinus rhythm, borderline left axis deviation, and borderline ST elevation in anterior leads?

Stress Test Selection for This EKG Pattern

For a patient with this EKG showing sinus rhythm, borderline left axis deviation, RSR' pattern in V1-V2, and borderline ST elevation in anterior leads consistent with early repolarization, a standard exercise ECG stress test is the most appropriate initial choice if the patient can exercise adequately. 1

Key EKG Interpretation Points

The described EKG findings do not represent contraindications to standard exercise ECG testing:

• RSR' pattern in V1-V2 is noted as "probably normal variant" and does not constitute complete left bundle branch block (LBBB) 1
• Borderline ST elevation with early repolarization is a benign finding that does not make the ECG "uninterpretable" for ischemia 1
• Borderline left axis deviation alone does not interfere with ST-segment interpretation 1

Recommended Testing Algorithm

If Patient Can Exercise (Preferred)

Standard exercise ECG testing is recommended as the first-line test because: 1

• The ECG remains interpretable for ischemia - the key contraindications that would make an ECG uninterpretable are: resting ST-segment depression ≥0.10 mV, complete LBBB, pre-excitation (WPW), LV hypertrophy with ST-T changes, paced rhythm, or digoxin use 1
• Exercise ECG provides simplicity, lower cost, and widespread availability 1
• It yields important prognostic information including heart rate response, blood pressure response, symptoms, and workload achieved 1

When to Upgrade to Stress Imaging

Exercise stress with imaging (echocardiography or nuclear MPI) should be considered if: 1

• Patient has intermediate-to-high pretest probability of coronary disease (10-90%) 1
• Patient is female - imaging studies demonstrate superior diagnostic accuracy in women compared to exercise ECG alone 1
• Additional prognostic information is desired beyond standard exercise testing 1

If Patient Cannot Exercise

Pharmacological stress testing with imaging is required: 1

• Vasodilator stress (adenosine/dipyridamole) with nuclear MPI is the preferred option 2
• Dobutamine stress echocardiography is an acceptable alternative 3, 4

Critical Distinction: This is NOT Complete LBBB

The RSR' pattern described as "probably normal variant" is fundamentally different from complete LBBB: 2

• Complete LBBB would require QRS duration ≥120 ms with specific morphologic criteria
• In true LBBB, exercise testing has poor specificity (33%) and accuracy (36-60%) due to false-positive septal perfusion defects 2
• In true LBBB, vasodilator stress testing is mandatory with superior sensitivity (98%), specificity (84%), and accuracy (88-92%) 2
• The described RSR' pattern does not meet these criteria and does not mandate pharmacological stress 1

Prognostic Considerations

Normal stress echocardiography provides excellent negative predictive value: 5, 6, 7

• Event-free survival of 97% at 30 months with normal stress echo 5
• Normal stress echo confers benign prognosis (1.1% annual event rate) independent of ECG findings 6
• Even with positive exercise ECG but normal stress echo, annual event rate remains low at 0.6% per year 6

Common Pitfalls to Avoid

• Do not automatically order imaging based on minor ECG variants like RSR' or early repolarization - these do not constitute "uninterpretable" ECGs 1
• Do not confuse incomplete RBBB or RSR' pattern with complete LBBB - only complete LBBB mandates pharmacological stress 2
• Do not order pharmacological stress in patients who can exercise with interpretable ECGs - this is specifically listed as Class III (no benefit) 1
• Ensure adequate exercise capacity - submaximal tests provide limited diagnostic and prognostic value 7